The subject invention is directed toward the art of fluid system devices and, more particularly, to an improved device and method of making the same.
The invention is especially suited for use in ball valves and will be described with particular reference thereto; however, as will become apparent, it could be used in many types of fluid system devices.
Many ball valves currently available comprise a main body section which houses the ball and seal rings. Attached to the opposite ends of the main body are end fittings which provide means by which the valve can be connected to associated piping or tubing. Typically, the end fittings and the body are interconnected by a plurality of tie bolts passing longitudinally through aligned openings in both the body and the end fittings. Appropriate seals are disposed between the end fittings and the body.
In order to replace the seals, however, it is necessary to remove the tie bolts and slide the body from between the fittings. This procedure is time consuming and, at times, presents difficulty in getting the body properly realigned with the fittings. Additionally, and with many designs, the associated piping must be moved before access to the seals is possible.
The subject invention overcomes the above problem and provides a flow system device which comprises a main central body section having a longitudinally extending through-flow passage and a valve ball mounted for rotation therein. A pair of end members, including flow openings, are positioned on longitudinally opposite ends of the body section with at least three tie bolts extending between the end members substantially parallel to the through-flow passage. Each tie bolt member passes through each end member with only one of the tie bolt members passing through the body section. The tie bolts are spaced circumferentially about the through-flow passage such that by removing one of the tie bolts adjacent to the bolt which extends through the body section, the body section can be pivoted outwardly from between the end members.
Although the arrangement is particularly suited for use in ball valves, the invention also contemplates that generally the same body, end fitting, and tie bolt relationships can be employed in many different devices used in fluid systems. For example, filters, flow gauges, sight gauges, check valves, and the like can advantageously be designed to use the inventive body or housing arrangement.
As can be appreciated, when the above arrangement is used in ball valves, seals can be changed by removing only a single tie bolt. Moreover, throughout the changing, the body section is held in position such that proper realignment is achieved merely by rotating the body back into its original position.
According to a more limited aspect of the invention, the body section is designed such that a portion of its exterior surface engages at least one of the bolts when it is in an aligned position between the end members. Preferably, at least one of the bolts which does not pass through the body section is positioned to engage portions of the exterior surface. Additionally, the body section is preferably of uniform cross-section throughout its length. Thus, the body section can be comprised of an extrusion in order to reduce machining time and manufacturing cost in a manner to be further discussed hereinafter. It is also contemplated that exterior portions of the body section will extend radially outward of the bolts an amount sufficient to permit the body section to be gripped by a wrench without engaging the bolts. This reduces the possibility of damaging the bolts while making connections to the end fittings.
In line with the previously discussed swing-out arrangement, the subject invention provides combined ball seat and body seal assemblies which can be removed and replaced as a unit to facilitate changing. In particular, the seal assemblies are adapted to be positioned in opposite ends of the through-flow passage of the body section and comprise a seat ring formed from a resilient material having a first surface arranged to engage the ball and a second surface, preferably planar, facing outwardly of the bore. A sleeve member closely encircles the seat ring and is adapted to be slidably received in a recess formed about the end of the bore. Encircling the sleeve member is a resilient seal ring, preferably an O-ring, which is adapted to provide a seal between the central body section and the end fittings. The end fittings also include surfaces which engage the second face of the seat ring and the seal ring when the body section is moved to its located position therebetween.
The provision of the sleeve between the seat ring and the seal ring prevents extrusion or cold flow of the seat ring outwardly between the body and the end fittings. Additionally, the sleeve provides a confined recess in which the O-ring is received. Because the O-ring member resiliently engages the outer surface of the sleeve, the entire assembly can be handled and inserted as a unit. Further, and in accordance with a more limited aspect of this feature of the invention, the inner surface of the sleeve includes a shoulder which confines the radial outward portion of the seat ring so as to, in effect, clamp it in order to hold the seat ring properly located with respect to the ball at all times. To simplify maintenance problems and to prevent improper reassembly, the seal assemblies on each side are preferably identical and/or interchangeable. However, for certain applications they could be different.
A further feature of the invention resides in the provision of an improved handle stop arrangement. As is well known, most ball valves are designed so that a 90.degree. movement of the operating handle moves the valve between the full open and full closed positions. Normally, it is desirable to provide stops at both extreme positions of handle movement; and for this purpose, stop pins are often positioned in the top of the valve body to extend upwardly for engagement of the lateral sides of the handle member at predetermined positions of movement. Alternatively, it has been known to form cast or somewhat complex machined handles with depending stop arrangements which engage machined stop surfaces or pins on the body. As one of its features, the subject invention provides a novel handle stop arrangement in which the handle member can be a simple stamping having a pair of tabs bent downwardly to provide stops which engage longitudinally extending surfaces formed on the body. According to this aspect of the invention, the improvement generally comprises first and second stop surfaces formed on the exterior of the valve and positioned on laterally opposite sides of the operating stem. The handle is connected to the stem for rotation thereof between the first and second spaced points which are normally 90.degree. apart. The handle includes first and second depending stop members bent downwardly from the plane of the handle with the first stop member being positioned to engage the first stop surface at the first position of rotation and the second stop member being positioned to engage the second stop surface at the second position of rotation. The stop members are located such that when they engage their respective stop surfaces, the contact forces act parallel to the plane in which the line of bend of the respective stop member lies.
By orienting the stop members relative to the stop surfaces in the manner described hereinabove, all forces acting against the bent stops act in the direction of greatest strength of the stops; that is, the forces do not act to produce an unbending of the bent metal stops. This permits the handle to be a simple metal stamping with the stops bent downwardly.
The invention also contemplates that the depending stops can only engage the valve body in the intended direction. The stops are located such that when one stop is in engagement with the valve body, the other stop is spaced a distance outwardly of the body. The handle stop is symmetrical to the centerline of the body, allowing the handle to be reversed 180.degree. and used as an indication of flow direction.
Because of the arrangement of the handle stops and the use of a simple stamping for the handle, the manufacturing effort is greatly simplified. This permits handles to be readily varied to suit specific different needs. For example, the handles can be varied in length, supplied for reversed position, mechanically actuated, locked, etc., with a minimum of complexity.
An additional feature of the invention resides in the provision of a stem packing arrangement particularly suited for the valve hereinabove described. In general, the stem packing arrangement includes a bore extending radially through the body which is provided with a flange or shoulder extending radially inward relative to the bore. The stem is sized so as to be freely rotatable within the bore flange and includes a stem flange adapted to extend outwardly beneath the bore flange. A thrust bearing member is positioned between the bore flange and the stem flange and a seal assembly is located above the bore flange. Additionally, a compression gland is positioned about the stem to engage the upper surface of the seal assembly. A gland nut is threadedly received on the outer end of the stem to compress the seal assembly and form a seal about the stem when tightened. Preferably, the thrust bearing member is split so that it does not inadvertently form a seal. Because of the arrangement of the flanges, the stem is blowout proof even when the packing is removed.